Device for building up down-pressure on well face during drilling

ABSTRACT

A well drilling rig provided with a device or detector capable of varying the shape and amplitude of dynamic forces acting upon the drill bit to raise the efficiency of well drilling in which the device is constituted by a cylinder-piston unit built into the drill string and the piston rod thereof having a through bore for the passage of the drilling fluid through the string.

United States Patent 1 1 Vasiliev et a1.

[451 Dec. 10, 1974 [54] DEVICE FOR BUILDING UP DOWN-PRESSURE ON WELLFACE DURING DRILLING [22] Filed: Mar. 14, 1973 [21] Appl. No.: 341,298

Related US. Application Data [63] Continuation of Ser. No. 102,674, Dec.30, 1970,

abandoned.

[30] Foreign Application Priority Data Jan. 7, 1970 U.S.S.R 1391730 [52]US. Cl. 175/321, 267/168 [51] Int. Cl E2lb 17/00 [58] Field of Search175/321, 299; 64/23, 1 V,

[56] References Cited UNITED STATES PATENTS 1,170,146 2/1916 Gallagher267/168 X 1,774,763 9/1930 Santiago... 175/321 X 2,113,651 4/1938Heaston.... 175/321 2,184,745 12/1939 Kinneman. 267/137 X 2,563,5158/1951 Brown 175/321 X 3,254,508 6/1966 Garrett..... 175/321 X 3,301,0091/1967 Coulter 175/321 X 3,383,126 5/1968 Salvatori et al.. 175/321 XFOREIGN PATENTS OR APPLICATIONS 7,465 5/1902 Austria 175/299 5/1932France 175/321 Primary Examiner-David H. Brown Attorney, Agent, orFirm-Holman & Stern [5 7 ABSTRACT A well drilling rig provided with adevice or detector capable of varying the shape and amplitude of dynamicforces acting upon the drill bit to raise the efficiency of welldrilling in which the device is constituted by a cylinder-piston unitbuilt into the drill string and the piston rod thereof having a throughbore for the passage of the drilling fluid through the string.

3 Claims, 2 Drawing Figures This in a continuation of application Ser.No.

102,674, filed Dec. 30, 1970, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to the drillstrings used in rigs for drilling wells in soil and rocks and morespecifically it relates to a device for building-up a downpressure onthe well face during drilling.

Such devices can be employed most successfully while drilling wells inhard rock which calls for a heavy axial pressure to be applied to thewell face.

PRIOR ART Widely known in the art are devices for building-up adown-pressure on the well face comprising a cylinder with a rod andpiston telescoping in said cylinder. This device is built coaxially intothe drill string so that the cylinder is secured to the upper pipe oftwo adjacent drill pipes while the rod is secured to the lower pipe.

Before starting the operation of the device the rod with the piston arebrought to the initial uppermost position. The lower part of the drillstring connected to the rod of the device rests, by its bit, on the wellface and is compressed whereas the upper part of the string, connectedto the cylinder of the device, is suspended from the hook of the surfacedrilling rig and is under tension.

In such devices, the down-pressure on the well face during drilling isbuilt up due to the difference of the hydraulic pressure of the fluidforced into the string and applied to the piston of the device. Thispressure is, by its nature, a static force transmitted from the pistonto the well face (via the rod of the device, the lower part of the drillstring and the bit) and ensures the drilling of the rock.

As the well face is gradually worked out and the well well face, butalso the magnitude and type of the dynamic component of said pressure.

SUMMARY OF THE INVENTION This object is achieved, according to theinvention, by constituting the piston of the device of coaxial alter- 4nating outer and inner cylindrical rings, with each of becomes deeper,the lower part of the drill string with the bit moves down and carriesdown the rod and piston connected thereto, moving them with relation tothe cylinder of the device. This continues until the piston reaches thedownmost position in the cylinder after which the upper part of thedrill string is fed down through the length of the piston travel and thedrilling process is continued.

One of the disadvantages of the known devices for building-up adown-pressure on the well face during drilling lies in that they createand change only the static component of the axial load applied to theface in the course of drilling. Also, it is known that the axialpressure on the well face includes also a dynamic component in the formof pulses caused by the axial vibra- 'tions of the drill bit while itscutters roll over the well .face.

I The drilling efficiency (penetration rate and drilling progress perbit) depends to a considerable measure upon the magnitude and type ofthe dynamic component of the axial pressure applied to the face.

An object of the present invention resides in eliminating the aforesaiddisadvantage.

The main object of the invention lies in providing a device forbuilding-up a down-pressure on the well face during drilling whichcreates and changes not only the static component of the axial pressureapplied to the said rings being in the form of a movable wedge locatedbetween the two adjacent rings. It is practicable that the outer andinner rings have respective inner and outer conical surfaces on theircontacting areas.

In one embodiment of the invention the outer and inner rings areinstalled movably on the rod between a circular flange located on theupper free end of the rod and a lower cover or closure of the cylinder.

In another embodiment of the invention, the outer and inner rings areinstalled movably on an extension of the upper pipe of the drill string,the lower end of said extension entering an axial channel of the rodwith a provision for axial movement therein, and said rings are locatedbetween the upper end of the rod and the upper end-plate of thecylinder.

Such a design of the device, according to the invention, permitsapplying a dynamic pressure to the well face by converting the pulses ofthe axial vibrations arising in the pipes of the drill string when thebit cutters roll over the well face. These vibrations are extended alongthe string in the form of stretching and compression pulses and reachthe device built into the string.

The set of coaxial cylindrical rings interacting with each other bytheir conical surfaces is a type of detector of drill pipe axialvibrations, with the detector either strengthening or weakening (asrequired) the compression (or stretching) pulses at the lower end of thedrill string.

BRIEF DESCRIPTION ON THE DRAWINGS Now the invention will be described indetail by way of examples with reference to the accompanying drawings inwhich:

DETAILED DESCRIPTION OF THE INVENTION The device for building-updown-pressure on the well face during drilling comprises acylinder 1(FIGS. 1 and 2) accommodating a hollow rod 2 provided with a piston 3telescoping in the cylinder 1.

The device is built coaxially into the drill string 4 between twojointed pipes 5 and 6 and has a through axial channel 7 for the passageof the drilling fluid through the device and the pipes of thestring 4,to a bit 8 which is rotated by a drill motor 9 secured to a lowermostpipe 10 of the string 4.

The upper part of the cylinder 1 is connected by a threaded joint 11 tothe adjacent upper drill pipe 5 of the string 4 while its lower part isclosed with a cover or end 1a having a bore for the passage of .thehollow rod 2. The upper free end of the rod2 located in the cylinder 1is provided with a circular flange 2 while the lower end of the rod 2 isconnected with the lower pipe 6 by means of a threaded joint l2.

.. rings 13 are an exception, since each of these rings has only oneconical surface 16 facing the adjacent inner ring 14.

In the first embodiment of the invention illustrated in FIG. 1 the outerand inner rings 13 and 14 are movably installed on the rod 2 between thecircular flange 2 and the cover 1a of the cylinder 1. In this form, therod 2 occupies the uppermost position in the cylinder 1.

The second embodiment of the device illustrated in FIG. 2, differs fromthe first one in that the rings 13a and 14a are installed'on andextension 17 of the upper pipe a of the drill string 4a, with the lowerend of said extension entering the axial channel in the rod 2a with aprovision for moving therein. The rings 13a and 14a are located betweenan upper end plate 18 of the cylinder and an upper end 19 of the rod 2awhich, in this form of the device, occupies the downmost position in thecylinder 1a. I

The device for building-up down-pressure on the well face duringdrilling functions as follows:

When the cutters (not shown) of the bit 8 roll over the well face, thiscreates axial vibrations of the string 4 above the bit 8; extendingupward along the string 4,

and these vibrations reach the rod 2 of the device in the form ofcompression and stretching pulses.

Subsequent operation of the device depends on i which one of theabove-described embodiments of the invention has been selected foremployment.

In the first form (FIG. 1) the stretching pulses move the rod 2 down andthe circular flange 2 of the rod movesdown the upper outer ring 13 whichcauses relative movement of the outer and inner rings 13 and 14 overtheir contacting conical surfaces 16 and '15.

Owing to the forces of friction occasioned by the relative movement ofthe rings 13 and 14, the stretching pulses are damped to a considerabledegree while the compression pulses reach the rod 2, are reflected byits upper free end (because the rings 13 and 14 function only undercompression) and return to the bit 8 in the form of tension half-waves.

In the second form of the device (FIG. 2) the stretching pulses move therod 2n down and, being reflected by its free end, return to the bit 8ain the form of compression pulses, while the compression pulses movethe' rod upward and are damped owing to friction arising when the rings13a and 14a interact over their matchfunctions as a detector of axialvibrations of the drillstring. This distinctive feature raisesconsiderably the efficiency of well drilling. What we claim is:

l. The combination with a drillvstring constituted by a plurality ofinterconnected pipes and a bit operably associated with the lower end ofthe drill string, of a device located in the drill string forbuilding-up a down pressure on the well face during drilling, saiddevice comprising: a cylinder, a rod provided with a piston located insaid-cylinder, said piston rod being provided with a through axial borefor the passage of a drilling fluid, and said piston being defined bycoaxial alternating outer and inner rings, with each of said inner ringsconstituting a wedge between the two adjacent outer rings whereby underthe influence of a compression pulse, the movable rings enter intocontact with one another partially passing and partially dissipating thecompression pulse while an extension pulse causes the rings to disengagefrom one another and define a boundary free surface from which theextension pulse is reflected and returns to the bit, subjecting the bitto a dynamic load, the drill string including a pipe adjacent thecylinder, said pipe having an extension, said outer and inner ringsbeing installed movably on the extension, said extension having a lowerend entering the axial bore of said rod with a provision for movingtherein, said rod having an upper end and an end plate on the upper endof the cylinder, said rings being located between the upper end of saidrod and the end plate of said cylinder.

2. The combination with a drill string constituted by a plurality ofinterconnected pipes and a rotary bit operably associated with the lowerend of the drill string, of a device located in the drill string forcontrolling a dynamic load on the rotary bit, said device comprising ahollow cylinder mounted coaxially between two adjacent pipes of saiddrill string, said cylinder having upper and lower end plates, saidupper end plate rigidly connecting the cylinder with an upper adjacentpipe of said drill string, said upper end plate having an axial throughopening, said lower end plate of said cylinder having an axial throughopening, a hollow cylindrical rod coaxially mounted in said cylinderwith a possibility of axial movements, a circular flange on the upperend of said rod, the lower end ofthe rod passing through the opening insaid lower end plate and being rigidly connected with a lower adjacentpipe of said drill string, outer rings mounted with a possibility ofaxiaLmovements on said rod between said circular flange and said lowerend plate of said cylinder, inner rings each of which is mounted with apossibility of axial movements on said rod between two adjacent outerrings, each of said outer rings being provided on its inner side with awedge-shaped projection defined by two conical sur faces, each of saidinner rings being provided on its outer side with a wedge-shapedprojection defined by two conical surfaces which, during the bitsoperation, periodically contact with the corresponding conical surfaceson the inner sides of said adjacent outer rings thereby resulting insuppressing the stretching pulses and during periodic intervals betweencontacts of said conical surfaces, stretching impulses reflect from thefree end of the rod and return to the bit 3. The combination with adrill string constituted by a plurality of interconnected pipes and arotary bit operably associated with the lower end of the drill string,of a device located in the drill stringfor controlling a dynamic loadvonthe rotary bit, said device comprising a hollow cylinder mountedcoaxially between two adjacent pipes of said drill string, said cylinderhaving upper and lower end plates, each of said end plates having athrough opening, said upper end plate rigidly connecting the cylinderwith an upper adjacent pipe of said drill string, a hollow cylindricalrod mounted coaxially in the cylinder with a possibility of axialmovements, a circular flange on the upper end of the rod, the lower endof the rod passing through the opening in the lower end plate and beingrigidly connected with a lower adjacent pipe of the drill string, abranch pipe mounted within said rod and rigidly connected at its upperend with said upper adjacent pipe of the drill string, outer ringsmounted with a possibility of axial movements on the branch pipe betweenthe circular flange on the rod and ing in suppressing the stretchingpulses and during perodic intervals between contacts of said conicalsurfaces, stretching pulses reflect from the free end of the rod andreturn to the bit.

1. The combination with a drill string constituted by a plurality ofinterconnected pipes and a bit operably associated with the lower end ofthe drill string, of a device located in the drill string forbuilding-up a down pressure on the well face during drilling, saiddevice comprising: a cylinder, a rod provided with a piston located insaid cylinder, said piston rod being provided with a through axial borefor the passage of a drilling fluid, and said piston being defined bycoaxial alternating outer and inner rings, with each of said inner ringsconstituting a wedge between the two adjacent outer rings whereby underthe influence of a compression pulse, the movable rings enter intocontact with one another partially passing and partially dissipating thecompression pulse while an extension pulse causes the rings to disengagefrom one another and define a boundary free surface from which theextension pulse is reflected and returns to the bit, subjecting the bitto a dynamic load, the drill string including a pipe adjacent thecylinder, said pipe having an extension, said outer and inner ringsbeing installed movably on the extension, said extension having a lowerend entering the axial bore of said rod with a provision for movingtherein, said rod having an upper end and an end plate on the upper endof the cylinder, said rings being located between the upper end of saidrod and the end plate of said cylinder.
 2. The combination with a drillstring constituted by a plurality of interconnected pipes and a rotarybit operably associated with the lower end of the drill string, of adevice located in the drill string for controlling a dynamic load on therotary bit, said device comprising a hollow cylinder mounted coaxiallybetween two adjacent pipes of said drill string, said cylinder havingupper and lower end plates, said upper end plate rigidly connecting thecylinder with an upper adjacent pipe of said drill string, said upperend plate having an axial through opening, said lower end plate of saidcylinder having an axial through opening, a hollow cylindrical rodcoaxially mounted in said cylinder with a possibility of axialmovements, a circular flange on the upper end of said rod, the lower endof the rod passing through the opening in said lower end plate and beingrigidly connected with a lower adjacent pipe of said drill string, outerrings mounted with a possibility of axial movements on said rod betweensaid circular flange and said lower end plate of said cylinder, innerrings each of which is mounted with a possibility of axial movements onsaid rod between two adjacent outer rings, each of said outer ringsbeing provided on its inner side with a wedge-shaped projection definedby two conical surfaces, each of said inner rings being provided on itsouter side with a wedge-shaped projection defined by two conicalsurfaces which, during the bit''s operation, periodically contact withthe corresponding conical surfaces on the inner sides of said adjacentouter rings thereby resulting in suppressing the stretching pulses andduring periodic intervals between contacts of said conical surfaces,stretching impulses reflect from the free end of the rod and return tothe bit.
 3. The combination with a drill string constituted by aplurality of interconnected pipes and a rotary bit operably associatedwith the lower end of the drill string, of a device located in the drillstring for controlling a dynamic load on the rotary bit, said devicecomprising a hollow cylinder mounted coaxially between two adjacentpipes of said drill string, said cylinder having upper and lower endplates, each of said end plates having a through opening, said upper endplate rigidly connecting the cylinder with an upper adjacent pipe ofsaid drill string, a hollow cylindrical rod mounted coaxially in thecylinder with a possibility of axial movements, a circular flange on theupper end of the rod, the lower end of the rod passing through theopening in the lower end plate and being rigidly connected with a loweradjacent pipe of the drill string, a branch pipe mounted within said rodand rigidly connected at its upper end with said upper adjacent pipe ofthe drill string, outer rings mounted with a possibility of axialmovements on the branch pipe between the circular flange on the rod andthe upper end plate of the cylinder, inner rings each of which ismounted with a possibility of axial movements on the branch pipe betweentwo adjacent outer rings, each of said outer rings being provided on itsinner side with a wedge-shaPed projection defined by two conicalsurfaces which, during the bit''s operation, periodically contact withcorresponding conical surfaces on the inner sides of said adjacent outerrings thereby resulting in suppressing the stretching pulses and duringperodic intervals between contacts of said conical surfaces, stretchingpulses reflect from the free end of the rod and return to the bit.